Genetics and Genomics Midterm 1

Comprehensive vocabulary flashcards covering basic genetics, Mendel's laws, DNA/RNA structure, replication processes, mutations, and repair mechanisms.

Genetics

The study of heredity and the roles and functions of single genes and variants.

Genomics

The study of whole organism genomes, including sequence, genetic mapping, and interactions between loci and alleles.

Pharmacogenomics

The use of genetic data to inform drug development and testing, particularly by relating individual variation to drug responses.

Law of Segregation (1st Law)

States that every individual possesses a pair of alleles for a particular trait and passes a randomly selected copy of only one to its offspring.

Law of Independent Assortment (2nd Law)

States that separate genes for separate traits are passed independently of one another from parents to offspring.

Autosomal Recessive Disorders

Genetic disorders characterized by the presence of two mutated alleles where an individual only has the disorder if they possess two abnormal alleles.

Gene

A DNA sequence that contains the necessary information to make a protein.

Locus

The specific position on a chromosome where a gene for a particular trait resides.

Genome

The complete DNA sequence of an organism containing all its genetic information.

Autosomes

All chromosomes except for the sex chromosomes; a diploid cell contains two copies of each.

Allele

One of the variant forms of a gene at a particular location on a chromosome that may produce variation in inherited characteristics.

Genotype

The internally coded heritable information or genetic constitution of an individual, consisting of the combination of alleles at a given locus.

Phenotype

The observable manifestation of a genotype.

Haplotype

The genotype of a group of alleles from two or more closely linked loci on one chromosome, usually inherited as a unit.

Mutation

Any permanent heritable change in the sequence of genomic DNA.

Polymorphism

Variations in DNA sequence that occur in greater than $1\%$ of the population.

Homozygous

Having identical alleles at a given locus.

Heterozygous

Having different alleles at a given locus.

Nucleotide

The monomeric unit of DNA consisting of a deoxyribose sugar, a purine or pyrimidine base, and a phosphate group.

Phosphodiester bond

The bond connecting the $3'$ position of one sugar to the $5'$ position of another sugar in a nucleic acid polymer.

Chargaff's Rules

The finding that purines and pyrimidines always appear in equal amounts, specifically $A:T$ and $G:C$, and vary between species.

Melting temperature ($T_m$)

The temperature at which half of the helical structure of DNA is lost; increased by high $GC$ content.

Nucleosome

The unit of chromatin consisting of a core particle of $146 \, \text{bp}$ and an octamer of histones including $2\times H2A$, $H2B$, $H3$, and $H4$.

Mitochondrial Genome

Circular DNA of $16.5 \, \text{Kb}$ transmitted maternally, not packaged into nucleosomes, and possessing its own protein synthesis.

mRNA

Messenger RNA used as a template for protein synthesis, containing codons and featuring a relatively short half-life.

5' Cap

A $7\text{-methylguanosine triphosphate}$ modification added to the $5'$ terminal of mRNA to protect from degradation and enhance translatability.

Poly(A) queue

A chain of about $250 \, \text{nt}$ of $AMP$ residues added posttranscriptionally to the $3'$ end of eukaryotic mRNA to enhance lifetime and translatability.

snRNA

Small sequences of RNA involved in spliceosomes that cut and edit mRNA in eukaryotes.

rRNA

Ribosomal RNA that provides the platform for protein synthesis; consists of large and short subunits.

tRNA

Transfer RNA that translates mRNA messages into polypeptides by attaching a specific amino acid at one end and using an anticodon at the other.

S-phase

The specific stage of the cell cycle during which DNA synthesis or replication occurs.

Semi-conservative replication

The mechanism where each new DNA molecule contains one newly synthesized strand and one parental strand.

Helicases

Proteins that perform $ATP\text{-driven}$ processive unwinding of double-stranded DNA.

Topoisomerases

Proteins that relieve torsional strain resulting from helicase-induced unwinding of DNA.

DNA ligase

Enzyme that seals the single strand nick between the nascent chain and Okazaki fragments on the lagging strand.

Reverse Transcriptase

An enzyme that reverses the central dogma by synthesizing DNA from an RNA template; found in retroviruses like HIV and in telomerase.

Telomeres

Repetitive DNA sequences ($TTAGGG$ in vertebrates) and proteins that form a capped end structure on chromosomes to protect them.

Transition

A point mutation where a purine is replaced by a purine ($A \rightarrow G$) or a pyrimidine by a pyrimidine ($C \rightarrow T$).

Transversion

A point mutation where a purine is replaced by a pyrimidine ($A \rightarrow C$ or $T$) or vice versa ($G \rightarrow C$ or $T$).

Silent mutation

A mutation that results in no change to the amino acid sequence of a protein.

Nonsense mutation

A mutation that changes a codon for an amino acid into a stop codon, causing chain termination.

Frameshift mutation

A mutation caused by the addition or deletion of nucleotides that changes the reading frame of the genetic sequence.

Excision Repair

The removal of defective DNA; includes base-excision repair (BER), nucleotide-excision repair (NER), and mismatch repair (MMR).

p53

A master regulator gene that stops cell division for DNA repair or triggers the destruction of cells damaged beyond repair.